1. Field of the Invention
The present invention relates to a detecting element to which plasmon resonance is applied, a detecting device, and a method of producing the detecting element.
2. Description of the Related Art
In recent years, a sensor utilizing localized plasmon resonance using metal fine particles has been attracting attention.
For example, Japanese Patent Application Laid-Open No. 2003-268592 discloses an invention in which mutually isolated metal particles are formed in a plurality of pores in anodized alumina to form a plasmon resonance device. In the device, by utilizing the pores in the anodized alumina, the metal particles can be regularly placed independently with an arbitrary uniform size in arbitrary arrangement, to thereby improve and stabilize sensor sensitivity.
Japanese Patent Application Laid-Open No. 2004-279364 discloses a sensor chip with the aim of providing a sensor having low optical noise and high sensitivity. The sensor chip includes a holding member having a plurality of micropores independent of each other along a direction substantially perpendicular to the surface, and metal fine particles held independently of each other in the plurality of micropores, and is characterized in that the holding member is formed from a transparent dielectric with uniform density.
However, in the inventions disclosed in Japanese Patent Application Laid-Open Nos. 2003-268592 and 2004-279364, the number of the metal fine particles held in one pore is actually one, and thus there has been a limit of the amount of gold particles held on a chip. Therefore, there has been a limit of the number of gold particles per unit area. Moreover, when it is attempted to form a plurality of metal fine particles in one pore, the metal fine particles come into contact with each other. Thus, the dimension and shape of the metal fine particles are likely to become nonuniform. In order to improve and stabilize sensor sensitivity as a plasmon resonance device, it is important that metal fine particles isolated from each other are provided in uniform size.
Moreover, the patent documents disclosing the above prior art technologies do not describe the shape of metal fine particles in detail. More specifically, the above-mentioned patent documents neither describe nor suggest the point of achieving an improvement in sensitivity by controlling the shape of gold particles.